Being fair, we saw what Loki did in Avengers, and while the Warriors Three don't have the magical tricks, they are probably bare minimum as physically capable as him, probably moreso. While taking on a whole army would probably be a *little* much ( if nothing else, I don't see any of them being fond of playing Catch The 2000 Lb Bomb ), I really can't see anything short of anti-tank weapons actually scratching them.